Hi Lohb,
Welcome to PB2 land! Yes, it's sad that the trend shifted from separate components to all-in-one uber-DAPs, especially when you consider the ridiculously buggy UIs found in every DAP other than those made by Sony, which themselves suffer from having only 10- or 15mW peak output into 16-Ohms. Our choices, today, are confined by the ignorance of the masses and manufacturers' reasonable desire to meet the demands of the majority.
But those of us who have an understanding of the audible benefits of mix-and-match separate components, no tolerance for poor software, headphones that come to life only when given 300mW into 32-Ohms or more, and a willingness to carry and use the now unfashionable "bricks" of stacked gear, which have been branded as "inconvenient" by the legions of former Beats owners, whose highest priority remains rooted in fashion as they consider size and battery life (diametrically opposed objectives) to be more important than anything else... We still have yesteryear's hardware at our disposal, obsolete and unappreciated though it may be!
Wow, that dounds horribly elitist, reading it back, but I'll let it stand. I do my best to educate the newcomers, but the lure of the herd is difficult to overcome. I did, very recently, manage to convince a PB2 owner not to sell it (via a PM exchange), despite the fact that I would love to have a 2nd PB2, in reserve, should mine fail irreparably, in some way.
The PB2 is not just a great balanced amp, it's a veritable laboratory. I've learned so much and my ears have become quite experienced at critical listening - a skill attainable by anyone with healthy hearing, if they put in the time - rolling op-amps with various headphones.
My OPA1611-equipped Meier Stepdance is still going strong, but it's a one trick pony, despite its superlative transparency and neutrality - it is all you could want in an amp for use with many combinations of DAC and headphone, but certainly not all, most prominently excluding the Senn HD800, AKG K550, and Beyer DT880 600 and T1, among headphones I've owned, unless you use a DAC that smears or colors the signal coming into the Stepdance (a deplorable practice, in my opinion, seen far too often, as with people using the Schiit Vali with an HD800, morphing it into something less than it's capable of being.)
The PB2, on the other hand, is a lump of clay, ready and willing to to play whatever role you ask of it. Well, it does have some limitations.
OK, that's enough of my tribute to the PB2.
Regarding fully balanced operation, you will have to use the balanced input of the PB2, not the TRS input, but I am strongly of the opinion that using balanced-output DACs is a waste of money, even for desktop amps, unless the distance to the amp is greater than three or four meters, where the benefits of common-mode noise rejection can actually be heard - or so they say, as I've never experienced going from a balanced DAC to unbalanced and back over a long cable run to the amp. I did so, using very short cables with the iBasso DB2 and could hear no benefits. The shorter your line level cables, the less benefit there is to going fully balanced, even theoretically, much less audibly.
Add to this my conviction that amps with both TRS and balanced output can sound better using balanced cables almost entirely due to the power increase had with going balanced, and not due to the mostly imagined benefits of common-mode noise reduction or cancellation of cross-channel impedance fluctuations. I genuinely believe such impairments to sound quality actually exist, as evidenced by Jan Meier's innovative implementation of his "Active Balance" feature in the Stepdance - where he injects a nulling signal to each transducer, to cancel the impedance fluctuations "felt" across the shared ground wire that can modulate the frequency response of dynamic headphones (not so much with the almost purely resistive planar magnetic headphones), BUT... I have never read any reviewers of any of the many uber-expensive desktop amps having only TRS output, tube or solid state, owned and loved by experienced afficianados of high-end gear, write anything close to a lament of this nature: "If only this otherwise supurb headphone amp had a balanced output to eliminate the cross-channel impedance fluctuations I'm hearing! It's got plenty of power, but the lack of common-mode noise rejection (on six-foot headphone cables) is another factor that earns this amp a big thumbs down!" Seriously, nobody complains of hearing these undesirable anomolies with single-ended amps. It's the benefits of additional power that people are hearing and enjoying by switching from a TRS jack to a 4-pin jack on amps that offer both, and even then, the power increase is audibly benefecial only when the transducers are sufficiently inefficient to perform their best with the power offered at the TRS jack.
The extremely popular and affordable Chinese-made Gustard H10 desktop amp offers both balanced and unbalnced inputs (for the sake of compatibility), yet only a TRS output! Bravo! They get it! But people wonder why it lacks balanced output! Ken Ball, of ALO, is on record as having defended his first portable amps, that had balanced input, but no balnced output, saying that the balanced input was just for compatibility with balanced portable DACs, while balanced output was unnecessary, given the amp's power at the TRS jack. He later succumbed to market pressure applied by the ill-informed masses, to produce amps with balanced output.
There are legions of very experienced, very satisfied, well-heeled users of single-ended amps that provide plenty of power for their headphones of choice, who couldn't care less about balanced output, much less, fully-balanced operation - because the benefits of sufficient power far outweigh any benefits of balanced operation, especially with short cable runs.
Mike
